I have a netbook that I'm running a 32 bit installation of lubuntu on, and the dropbox icon works fine there...I figured I'd try to install another desktop environment to see if that would help. Apparently it's pretty easy, and this article does a good job of explaining it:
Basically, it's super easy to install another desktop environment and switch which one you want to load upon login. I decided I'd try lubuntu here's what I did:
install the desktop environment via terminal (you could use the software center too though)
sudo apt-get install lubuntu-desktop
after it was done, shut down the computer
boot into xubuntu. At the login screen, in the upper right next to the batter icon, there's a little xubuntu icon...click that, and it gives you a choice of what session to log in as. I didn't even know this, but apparently there's an 'xfce session' option and a 'xubuntu' session option....being curious, i clicked on the 'xfce session' option, and logged in....and voila! dropbox icon was back.
Now that the icon was back, I tried it for the regular 'xubuntu' login session and it works for that too. And of course it woks for the lubuntu sessions as well.
So that seemed to do it! hopefully it works for you guys too!
I have also posted this on http://ubuntuforums.org/showthread.php?t=2225969&page=2